Improved thermal stability of Al2 O3 / HfO 2 / Al2 O3 high-k gate dielectric stack on GaAs

Abstract

Thermal stability of HfO2 high-k gate dielectric on GaAs is investigated. Compared to HfO2 gate dielectric, significant improvements in interfacial properties as well as electrical characteristics were found by constructing a Al2 O3 / HfO2 / Al2 O3 dielectric stack. At elevated temperatures, the amorphous Al2 O3 layers were effective in inhibiting crystallization of HfO2. Since the passivating Al2 O 3 layers prevent interfacial oxide and trap charge formation, it aids in reducing the increasing rate of equivalent oxide thickness as well as capacitance-voltage hysteresis. Transmission electron microscopy and x-ray photoelectron spectroscopy data supported the improved electrical characteristic of GaAs metal-oxide-semiconductor capacitors with Al2 O3 / HfO2 / Al2 O3 gate dielectric stack. © 2010 American Institute of Physics.